pyrixos-ed25519

Ed25519 signatures, as RFC 8032 section 5.1 defines them, in Python with no compiled code and no dependencies. PyrixOS uses it to sign and check its binary cache, so its build tools need no Rust or C extension.

pip install pyrixos-ed25519

from pyrixos_ed25519 import BadSignatureError, SigningKey, VerifyingKey

key = SigningKey.generate()            # or SigningKey(seed), 32 bytes
signature = key.sign(b"message")       # 64 bytes
public = key.verifying_key.encoded     # 32 bytes

try:
    VerifyingKey(public).verify(signature, b"message")
except BadSignatureError:
    ...

Keys and signatures are the raw byte strings of RFC 8032, so they interoperate with OpenSSL, libsodium and the cryptography package. The tests check the RFC's vectors and, when cryptography is installed, compare signatures with it.

Verification rules

verify refuses a signature whose S is not less than the group order, and a public key or R that is not a canonical encoding of a curve point. It checks [S]B - [k]A against R without multiplying by the cofactor, the rule OpenSSL and libsodium follow.

Limits

Python integers give no constant-time arithmetic, so signing time depends on the secret key. Use the package where an attacker cannot time many signatures, such as signing build outputs on a build host. Signing takes about 2 ms and verification about 10 ms on a current x86_64 core.

Development

pip install --group dev
pip install -e .
pybootstrap check

License

GPL-2.0-only. See LICENSE.